Prevention of Spoofing in Telecommunications Systems

1. A method comprising: activating, in a first subsystem of a telecommunications systems, a packet data address for a terminal, the packet data address being activated for transmitting data packets between the terminal and a second subsystem; storing the packet data address in at least one node of the first subsystem via which node the data packets of the packet data address are routed; receiving in said node the packet sent from the terminal, the packet comprising a destination address and a source address; checking in said node whether the source address of the packet is the same as the packet data address; and transmitting the packet from the node towards the destination address only if the addresses are identical.

2. The method of claim 1 , further comprising: maintaining information on first packet data address types in said node, the information including at least one packet data address type on which said check is performed; and performing said check only if the packet data address is of the first packet data address type.

3. The method of claim 2 , wherein the first packet data address type includes at least an IP address according to the Internet protocol.

4. The method of claim 1 wherein said node is the gateway support node of the first subsystem which routes the data packet from the terminal to the second subsystem.

5. The method of claim 1 wherein said node is a support node which serves the mobile station and routes the packet received from the terminal forward in the first subsystem.

6. The method of claim 1 wherein the first subsystem is a packet radio network which uses a general packet radio service tunneling protocol and in which the packet data address is activated by activating the corresponding packet data protocol context.

7. The method of claim 2 , wherein said node is the gateway support node of the first subsystem which routes the data packet from the terminal to the second subsystem.

8. The method of claim 2 , wherein said node is a support node which serves the mobile station and routes the packet received from the terminal forward in the first subsystem.

9. The method of claim 2 , wherein the first subsystem is a packet radio network which uses a general packet radio service tunnelling protocol and in which the packet data address is activated by activating the corresponding packet data protocol context.

10. A method comprising: activating, in a first subsystem of a telecommunications system, a packet data address for a terminal, the packet data address being activated for transmitting data packets between the terminal and a second subsystem; storing the packet data address in at least one node of the first subsystem via which node the data packets of the packet data address are routed; receiving in said node the packet sent from the terminal, the packet comprising a destination address and a source address; defining the packet data address as a set of allowed packet data addresses; checking in said node whether the source address of the packet belongs to the set of allowed packet data addresses; and transmitting the packet from the node towards the destination address only if the source address of the packet belongs to the set of allowed packet data addresses.

11. The method of claim 10 , further comprising: maintaining information on first packet data address types in said node, the information including at least one packet data address type on which said check is performed; and performing said check only if the packet data address is of the first packet data address type.

12. The method of claim 11 , wherein the first packet data address type includes at least an IP address according to the Internet protocol.

13. A network node comprising means for receiving a packet; means for activating at least one packet data address for a terminal which the terminal can use when transmitting data packets; means for attaching a packet received from the terminal to the packet data address used by the terminal; means for comparing a source address of the packet with the packet data address used by the terminal; and means for sending the packet from the network node towards the destination address of the packet only if the addresses are identical.

14. A network node comprising means for receiving a packet; means for activating at least one packet data address for a terminal which the terminal can use when transmitting data packets, the packet data address being defined as a set of allowed packet data addresses, means for attaching a packet received from the terminal to the packet data address used by the terminal; means for checking whether a source address of the packet belongs to the set of allowed packet data addresses of the packet data address used by the terminal; and means for sending the packet from the network node towards the destination address of the packet only if the source address belongs to the set of allowed packet data addresses.